A restraint system in a vehicle can detect an impact of the vehicle from multiple directions. Based on the direction of the impact, the restraint system may use different sensors to detect the impact. Forward and rear collisions may use accelerometers to detect a sudden change in vehicle acceleration. An impact to a side of the vehicle may use an air pressure sensor located within a cavity formed by an inner door panel and an exterior door panel of the vehicle. The cavity formed by the inner and outer panels is typically not an air tight cavity, but allows for a predetermined flow of air in to and out of the cavity. This flow of air may be associated with many conditions including a change in a temperature around the vehicle, a change in an elevation of the vehicle, or a movement of a door of the vehicle such as closing the door. When the vehicle experiences an impact to a side door of the vehicle, the exterior door panel may compress thus causing a reduction in an area of the cavity between the inner and outer door panels. The reduction in the area of the cavity results in an increase in air pressure within the cavity. The increase in air pressure is in relation to the ambient air pressure around the vehicle. An air sensor may measure this increase in air pressure and output a signal indicative of the increase in air pressure. The signal may trigger a restraint control module to inflate a side air bag.